Definition 2.2 (Individual discrimination [1]}) 

A model \(f_\theta (x)\)  is said to be nondiscriminatory between individuals if the following holds:
\(\forall x = (x_s, x_{ns}),x^{\prime } =(x^{\prime }_s, x^{\prime }_{ns}) \in D_\phi \quad \text{s.t.} \quad x_{ns} = x^{\prime }_{ns} \; \text{and} \; x_s \ne x^{\prime }_{s} \Longrightarrow h(f_\theta (x)) = h(f_\theta (x^{\prime })),\) 
